This application claims the priority of German Application No. 197 22 253.6, filed May 28, 1997, the disclosure of which is expressly incorporated by reference herein.
The invention relates to an electronic bucking damping device for internal-combustion engines with an electronic fuel injection in motor vehicles, particularly diesel engines, having a quantity request signal which can be defined by an accelerator pedal and is fed to a fuel injection device, and having a quantity component signal which is derived from the bucking vibration superimposed on the rotational speed signal of the internal-combustion engine and is supplied in an inverse-coupled manner to the fuel injection device.
In order to avoid load jumps and a related uncomfortable vehicle handling in the case of motor vehicles with electronic fuel injection, the quantity request signal definable by way of the accelerator pedal must be filtered in a suitable manner. However, despite the filtering of the quantity request signal, vibration-type excitations of the transmission line are possible. This results in a so-called "bucking" vehicle handling. This bucking can be damped in a known manner in that the bucking vibration superimposed on the rotational speed signal is inversely-coupled to the injection quantity signal by way of a filter arrangement.
The known filter arrangements used for this purpose are relatively complex and have a relatively confusing construction because of the couplings and inverse couplings and are therefore difficult to apply.
It is an object of the present invention to provide an effective and comfortable bucking damping device which is easy to apply.
According to the invention, this object is achieved in that the quantity request signal is present by way of a filter with proportional (P), differentiating (D), and time delay (T) functions of the first (1) order PDT1-filter at a summation point connected with the control signal input of the fuel injection device, and the rotational speed signal filtered by way of a separate filter with differentiating (D) function of the second (2) order and a delay function (T) of the second (2) order D2T2-filter is present at this summation point as the quantity component signal to be subtracted.
According to the invention, the quantity damping and bucking damping functions were uncoupled by the two separate filters so that they can be adjusted and optimized independently of one another, whereby the desired simplified application is achieved. The filter functions are simpler and easier to understand and optimize. A PDT1-filter was found to be most suitable for the quantity damping and a D2T2-filter was found to be must suitable for the bucking damping.
The measures indicated herein permit advantageous further developments and improvements of the bucking damping device according to the present invention.
In the case of a vehicle, the amplitude and the frequency of the bucking vibrations are very dependent on the operating point, in which case the significant influencing quantities are the respective existing gear position and the rotational engine speed. Advantageously, for defining at least one portion of the filter parameters for the characteristic filter diagrams, characteristic diagrams are provided for the filters, in which case the filter parameters by way of these characteristic diagrams can be defined at least as a function of the rotational speed of the internal-combustion engine and/or of the respective existing gear position of the transmission in order to achieve, in all operating conditions, a respective optimal damping of the bucking.
It was also found to be advantageous to provide at least one switch-over device for changing over between a characteristic-diagram-dependent defining of filter parameters and a defining of fixed filter parameters, in which case a change-over of the change-over devices to the fixed filter parameters is provided in the case of external quantity interventions which require a fast reaction of the fuel injection device, and in which case the fixed filter parameters reduce or eliminate the filtering effect of the filters. As a result, it is, for example, ensured that, in the event of a start of an anti-slip control device (ASR), the internal-combustion engine will react in an undelayed manner.
As an alternative, it is also possible to provide that one filter or both filters can be bridged by a switching device in the case of external engine interventions which require a fast reaction of the fuel injection device. This also prevents the delay of the quantity request by filters if certain fast quantity interventions are required.
The bucking damping device according to the invention is mainly suitable for diesel engines with an electronically controlled injection pump.